Reliance is made generally upon the normal printing technique for formation of images on objective bodies. For the execution of the printing technique, provision and use of printing plates (forms or blocks) are requisite. No matter how simple the image-printing is, the plate-making is a very time-consuming the laborious procedure This is much more so in the printing of various and complexed image combinations, such as those of graphic or portrait images combined with characters, letters or bar codes, as an example, representing extremely complicated and troublesome work.
Further, in the normal printing operation, various operating conditions, including ink selection and the like, must be carefully considered, depending upon the kind and nature of the printing object, thus the best selection thereof is highly delicate and not as simple as expected.
The present invention is proposed upon careful consideration of the foregoing facts, and an object of the invention is to provide a unique process for the formation of sharp and clear images regardless of the kind and nature of the object to be printed upon, and usable and effective materials and apparatuses for carrying out this unique process.
The method of thermal image transfer (sublimation image transfer) on clothes or fabrics with the use of thermal transfer dyestuffs has been practiced for a long time. In this conventional process, a dyestuff picture layer carrying thermal transfer dyestuff is formed on a substrate sheet which is then subjected to heat in an overlapped state on a cloth or fabric, the dyestuff thereby being transferred thermally onto the latter for forming the desired images thereon. By utilizing this technique, and with recent development of the image forming technology concerning fine thermal printers and the like, various fine image forming processes have been proposed to provide fine images which are comparable to photographic images and are transferred onto plastic films from thermal transfer sheets carrying thermal transfer dyestuffs.
According to these recently proposed processes, various images of cameras, or TVs, graphic images of personal computers and the like can be reproduced easily in the form of hard copies on the surface of a transferred material such as a paper or the like sheet carrying thereon a fixedly attached layer of polyester resin, as an example. These images thus reproduced represent an amply high level comparable to those obtained by photography or fine printing arts.
The thermal transfer process so far set forth has an advantage in that it can form any image in a convenient manner yet entails a problem in that it is limited to image-transferred products preferably of polyester and the like materials which must be dyed with thermal transfer dyes. On the other hand, the image-transferred products must be limited to specifically selected shapes, preferably film, sheet or the like configuration, and thus, such materials as wood, metal, glass or ceramics cannot be formed with images in this way. Further, even if the material is plastics such as polyester or the like, and when the image-forming surface is curved or undulated, or physical body other than sheet, even if it represents a plane surface, it is almost impossible to reproduce images precisely thereon, which naturally constitutes a grave problem in the art.
With recent development and enlargement of utilizing fields of various card-style products, such as cash cards, telephone-cards, prepayment cards; and ID-cards, there are increasing demands for providing these cards with images, symbols and codes, so as to give various other functional and/or decorative effects. Most of these cards are of planar form, but they are frequently not pliable and/or have uneven rough portions due to provision of characters and symbols, resulting in great difficulty in the scheduled image formation relying upon the thermal image transfer process.
There is therefore an urgent demand among those skilled in the art for the provision of a unique technique capable of forming sharp and clear images of desired patterns on the surface of an objective body of any preferred kind of material and having any shape and configuration and surface condition of any kind, and indeed, for combining and unifying image- and decoration effects.